Plasma spraying of abrasive coatings

摘要

In the plasma spray deposition of an abrasive grit coating on a substrate, abrasive grit particles are injected into a high temp. plasma stream at a location downstream of the location at which matrix material particles are injected, in a direction 180 deg. apart at the plasma stream circumference from the direction of matrix particle injection and at a distance from the substrate such that the matrix particles and the grit particles come into simultaneous contact with the substrate surface and with each other. The plasma stream is traversed across the substrate. - Also claimed is the plasma spray deposition of a grit-contg. coating onto a narrow substrate, in which the substrate is offset from the plasma spray stream axis during coating to avoid the erosive zone at the axis of the spray. - The process is useful in the gas turbine engine industry, e.g., in the prodn. of interstage gas path seals between rotor and stator assemblies. Economical coatings with good adhesion and angularity of grit particles are achieved. DEAB- DE3317094 C Abrasive medium coating is applied to a substrate, partic. contact surface of a gas turbine, by using a plasma spray gun, in which a stream of plasma gases is produced within a plasma generator and directed on to the substrate. Particles of a matrix material are sprayed into the plasma stream remote from the substrate surface, while abrasive particles are injected into the plasma stream in the direct vicinity of the surface, particles of each constituent coming into contact with the surface at the time. Pref. particle injection of matrix and abrasive materials is displaced by about 180 deg. w.r.t. the plasma stream.